diff --git a/CMakeLists.txt b/CMakeLists.txt
index f279e5a3e..3bbb8de3e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -37,6 +37,11 @@ SET(GLOBAL_VERSION "${VERSION}")
 ## Optional
 set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/module" CACHE INTERNAL "Cmake module" FORCE)
 include(FindDoxygen OPTIONAL)
+if(NOT DOXYGEN_FOUND)
+    message(WARNING "Doxygen was not found, install it if you want to generate the documentation.")
+else()
+    message(STATUS "Doxygen found, use the target `doc` to generate the documentation.")
+endif()
 
 ######################################################################################
 ### 3) Include CMake files
diff --git a/cmake/Target.cmake b/cmake/Target.cmake
index 06fc26162..30d60f531 100644
--- a/cmake/Target.cmake
+++ b/cmake/Target.cmake
@@ -11,22 +11,119 @@ endif(UNIX)
 ######################################################################################
 
 if(DOXYGEN_FOUND AND DOXYGEN_EXECUTABLE)
-    if(SMP)
+    # FIXME this would work in cmake 3.13
+    # set(DOC_EO "make doc-eo")
+    # if(NOT EO_ONLY)
+    #     set(DOC_MO "make doc-mo")
+    #     set(DOC_MOEO "make doc-moeo")
+    #     if(EDO)
+    #         set(DOC_EDO "make doc-edo")
+    #     else()
+    #         set(DOC_EDO "")
+    #     endif()
+    #     if(SMP)
+    #         set(DOC_SMP "make doc-smp")
+    #     else()
+    #         set(DOC_SMP "")
+    #     endif()
+    #     if(MPI)
+    #         set(DOC_MPI "make doc-mpi")
+    #     else()
+    #         set(DOC_MPI "")
+    #     endif()
+    # endif()
+    #
+    # add_custom_target(doc
+    #     COMMAND ${DOC_EO}
+    #     COMMAND ${DOC_MO}
+    #     COMMAND ${DOC_MOEO}
+    #     COMMAND ${DOC_EDO}
+    #     COMMAND ${DOC_SMP}
+    #     COMMAND ${DOC_MPI}
+    # )
+    # FIXME in the meantime, we must enumerate...
+    if(EO_ONLY)
         add_custom_target(doc
             COMMAND make doc-eo
-            COMMAND make doc-edo
-            COMMAND make doc-mo
-            COMMAND make doc-moeo
-            COMMAND make doc-smp
         )
     else()
-        add_custom_target(doc
-            COMMAND make doc-eo
-            COMMAND make doc-edo
-            COMMAND make doc-mo
-            COMMAND make doc-moeo
-        )
-    endif()
+        # No optional module.
+        if(NOT EDO AND NOT SMP AND NOT MPI)
+            add_custom_target(doc
+                COMMAND make doc-eo
+                COMMAND make doc-mo
+                COMMAND make doc-moeo
+            )
+        endif()
+
+        # One optional module.
+        if(EDO AND NOT SMP AND NOT MPI)
+            add_custom_target(doc
+                COMMAND make doc-eo
+                COMMAND make doc-mo
+                COMMAND make doc-moeo
+                COMMAND make doc-edo
+            )
+        endif()
+        if(NOT EDO AND SMP AND NOT MPI)
+            add_custom_target(doc
+                COMMAND make doc-eo
+                COMMAND make doc-mo
+                COMMAND make doc-moeo
+                COMMAND make doc-smp
+            )
+        endif()
+        if(NOT EDO AND NOT SMP AND MPI)
+            add_custom_target(doc
+                COMMAND make doc-eo
+                COMMAND make doc-mo
+                COMMAND make doc-moeo
+                COMMAND make doc-mpi
+            )
+        endif()
+
+        # Two optional modules.
+        if(NOT EDO AND SMP AND MPI)
+            add_custom_target(doc
+                COMMAND make doc-eo
+                COMMAND make doc-mo
+                COMMAND make doc-moeo
+                COMMAND make doc-smp
+                COMMAND make doc-mpi
+            )
+        endif()
+        if(EDO AND NOT SMP AND MPI)
+            add_custom_target(doc
+                COMMAND make doc-eo
+                COMMAND make doc-mo
+                COMMAND make doc-moeo
+                COMMAND make doc-edo
+                COMMAND make doc-mpi
+            )
+        endif()
+        if(EDO AND SMP AND NOT MPI)
+            add_custom_target(doc
+                COMMAND make doc-eo
+                COMMAND make doc-mo
+                COMMAND make doc-moeo
+                COMMAND make doc-edo
+                COMMAND make doc-smp
+            )
+        endif()
+
+        # Three optional modules
+        if(EDO AND SMP AND MPI)
+            add_custom_target(doc
+                COMMAND make doc-eo
+                COMMAND make doc-mo
+                COMMAND make doc-moeo
+                COMMAND make doc-edo
+                COMMAND make doc-smp
+                COMMAND make doc-mpi
+            )
+        endif()
+
+    endif(EO_ONLY)
 endif(DOXYGEN_FOUND AND DOXYGEN_EXECUTABLE)
 
 ######################################################################################
diff --git a/edo/CMakeLists.txt b/edo/CMakeLists.txt
index 50424db45..b32c874cb 100644
--- a/edo/CMakeLists.txt
+++ b/edo/CMakeLists.txt
@@ -26,8 +26,8 @@ endif()
 ### Include subdirectories
 ######################################################################################
 
-add_subdirectory(doc)
 add_subdirectory(src)
+add_subdirectory(doc)
 
 if(ENABLE_CMAKE_TESTING AND EIGEN3_FOUND)  # see edoNormalAdaptive
     add_subdirectory(test)